Fetal abdominal wall defects and mode of delivery: a systematic review

OBJECTIVE

To determine whether there is sufficient evidence to support cesarean delivery over vaginal delivery in women carrying a fetus with an abdominal wall defect.

DATA SOURCES

An OVID MEDLINE search of English language abstracts using medical subject heading terms "gastroschisis," "omphalocele," and "fetal abdominal wall defects" was performed. The generated list of articles was supplemented by a review of their bibliographies and the bibliographies of obstetric texts.

STUDY SELECTION

A total of 27 peer-reviewed observational studies were identified, and 15 were included in the meta-analysis. Our primary inclusion criterion was the reporting of neonatal outcomes for infants with abdominal wall defects who delivered vaginally and who delivered by cesarean section. Studies were excluded if they were a case series or if neonatal outcomes could not be ascertained from the data presented in the manuscript.

TABULATION, INTEGRATION, AND RESULTS

Standard meta-analytic techniques were applied to assess the question of whether cesarean delivery improves neonatal outcomes in infants with abdominal wall defects. There was no significant relationship between mode of delivery and the rate of primary fascial repair (random effects model: pooled relative risk [RR] 1.22, 95% confidence interval [CI] 0.99, 1.51), neonatal sepsis (random effects model: pooled RR 0.70, 95% CI 0.30, 1.62), or pediatric mortality (random effects model: pooled RR 1.14, 95% CI 0.59, 2.21). Additionally, there was no significant relationship between mode of delivery and time until enteral feeding or length of hospital stay.

CONCLUSION

The available data do not provide evidence to support a policy of cesarean delivery for infants with abdominal wall defects.

Predicting outcomes of trials of labor in women attempting vaginal birth after cesarean delivery: a comparison of multivariate methods with neural networks

OBJECTIVE

Our aim was to assess the utility and effectiveness of a neural network for predicting the likelihood of success of a trial of labor, relative to standard multivariate predictive models.

STUDY DESIGN

We identified 100 failed trials of labor and 300 successful trials of labor in women with a prior cesarean delivery performed at our institution. Information was collected on >70 potential predictors of labor outcomes from the medical records, including demographic, historical, and past obstetric information, as well as information from the index pregnancy. Bivariate analyses comparing women in whom a trial of labor failed with those whose trial succeeded were performed. These initial analyses were used to select variables for inclusion into our muitivariate predictive model. From the same data we trained and tested a neural network, using a back-propagation algorithm. The test characteristics of the multivariate predictive model and the neural network were compared.

RESULTS

From the bivariate analysis a history of substance abuse (adjusted odds ratio, 0.27; 95% confidence interval, 0.09-0.80), a successful prior vaginal birth after cesarean delivery (adjusted odds ratio, 0.13; 95% confidence interval, 0.05-0.31), cervical dilatation at admission (adjusted odds ratio, 0.53; 95% confidence interval, 0.31-0.88), and the need for labor augmentation (adjusted odds ratio, 2.15; 95% confidence interval, 1.14-4.06) were ultimately discovered to be important in predicting the likelihood of the success or failure of a trial of labor. With these variables in the predictive model the sensitivity of the derived rule for predicting failure was 77%, the specificity was 65%, and the overall accuracy was 69%. We also built a network using the 4 variables that were included in the final multivariate model. We were unable to achieve the same degree of sensitivity and specificity that we observed with the regression-based predictive model (sensitivity and specificity, 59% and 44%).

CONCLUSION

In this study a standard multivariate model was better able to predict outcome in women ttempting a trial of labor.

The controversy surrounding indomethacin for tocolysis

Indomethacin is a prostaglandin synthetase inhibitor sometimes used for tocolysis. Several placebo-controlled trials and trials comparing indomethacin to other potential first-line tocolytic agents support its efficacy for delaying delivery for >48 hours. Recent observational studies, however, have raised concerns about the safety of indomethacin, implicating it with increased rates of intraventricular hemorrhage and necrotizing enterocolitis. Careful analysis of these observational studies suggests that these results should be viewed with caution, because of uncontrolled confounding by indication. A recent decision analysis supports the risk/benefit analysis of indomethacin in this setting. Still, the future of indomethacin in preterm labor should be guided by well-designed prospective clinical trials. Such studies are underway.